1. Field of the Invention
The present invention relates to a technique of analyzing, as to an electronic device, a route of a noise crosstalking from a plurality of noise source candidates into a terminal that have low tolerance to a noise, by electromagnetic field analysis.
2. Description of the Background Art
As the operating frequency of digital devices accelerates in recent years, problems related to noises such as malfunction of devices due to unnecessary radiation or deterioration in the quality of power supplies and signals are becoming obvious. This is attributed to an increase in an electromagnetic effect of the three-dimensional shape of the peripheral wiring such as a printed substrate associated with the acceleration of the operating frequency.
One of the noise problems is that, into an input to an analog circuit, a noise of an accelerated digital signal in the same device mixes via a route that is not intended by the designer, whereby malfunction occurs or the desired performance cannot be ensured. In designing devices, it is very effective to analyze the route of a crosstalking noise in dealing with the problem.
In conventional designing, a noise crosstalk route has been estimated through measurement of actual equipment such as a prototype. However, the measurement with the actual equipment requires various measurement techniques and complicated operations. Moreover, the measurement of a high speed signal itself is becoming more difficult, along with the acceleration of the operating frequency.
Accordingly, as methods of estimating a noise crosstalk route, attempts to employ analyzing schemes such as circuit analysis, electromagnetic field analysis and the like have been made, in place of the measurement with actual equipment. In particular, as to the electromagnetic field analysis, there are recent reports on attempts of applying three-dimensional electromagnetic field analysis having been used for designing antennas and the like to printed substrates and the like in cooperation with circuit analysis.
For example, Nikkei Electronics, Nikkei Business Publications, Inc., Jan. 31, 2005, pp. 117-130 discloses an example of dealing with noise problems on a printed substrate by using a plurality of computers to process in parallel electromagnetic field analysis by FDTD (Finite Difference Time Domain) method and circuit analysis. Japanese Patent Laying-Open No. 2004-054642 discloses a method relating to a method of accelerating the aforementioned analysis.
Although the electromagnetic field analysis is very effective in analyzing the mechanism of noise problems associated with digital devices as described in the aforementioned Nikkei Electronics, the time required for the analysis becomes enormously long as the target of analysis becomes vast and minute.
In analyzing a printed substrate or the like in which a plurality of terminals that are possibly the noise source (hereinafter also referred to as “noise source candidates”) exist, it is necessary to note the following points in analyzing a noise mixing route.
When performing the electromagnetic field analysis by applying a noise simultaneously to every noise source candidate, the electromagnetic field analysis is only necessary to be performed once. However, since the effects of all the noise source candidates are overlapping, it is very difficult to specify the source of a noise crosstalking in a certain terminal.
On the other hand, when performing analysis sequentially by applying a noise in turn to every noise candidate, it is possible to analyze the route of a noise from each noise source candidate to a certain terminal. However, since the electromagnetic field analysis must be performed as many times as the number of the noise candidates, the analysis time becomes enormously long.